31 C.F.R. § 363.205 How do I reinvest the proceeds of a maturing security held in TreasuryDirect® ?
Title 31 - Money and Finance: Treasury
You can reinvest the proceeds of a maturing security held in TreasuryDirect by first directing that the proceeds from the maturing security be used to purchase a certificate of indebtedness in your account, and then using the redemption proceeds of your certificate of indebtedness to purchase another security. Any purchase using the proceeds from a certificate of indebtedness is considered a reinvestment.
Title 31: Money and Finance: Treasury
PART 363—REGULATIONS GOVERNING SECURITIES HELD IN TREASURYDIRECT
Subpart F—Marketable Treasury Securities
§ 363.205 How do I reinvest the proceeds of a maturing security held in TreasuryDirect